Parallel ledger loader & I/O performance improvements:

- Only duplicate records from archive to writable during online_delete.
- Log duration of nodestore reads.
- Include nodestore counters in perf_log output.
- Remove gratuitous nodestore activity counting.
- Report initial sync duration in server_info and perfLog.
- Report state_accounting in perfLog.
- Make state_accounting durations more accurate.
- Parallel ledger loader.
- Config parameter to load ledgers on start.

src/ripple/app/main/Application.cpp

@@ -279,6 +279,7 @@ public:
               perf::setup_PerfLog(
                   config_->section("perf"),
                   config_->CONFIG_DIR),
+              *this,
               logs_->journal("PerfLog"),
               [this] { signalStop(); }))
 
@@ -1312,6 +1313,7 @@ ApplicationImp::setup()
     Pathfinder::initPathTable();
 
     auto const startUp = config_->START_UP;
+    JLOG(m_journal.debug()) << "startUp: " << startUp;
     if (!config_->reporting())
     {
         if (startUp == Config::FRESH)
@@ -1333,7 +1335,18 @@ ApplicationImp::setup()
             {
                 JLOG(m_journal.error())
                     << "The specified ledger could not be loaded.";
-                return false;
+                if (config_->FAST_LOAD)
+                {
+                    // Fall back to syncing from the network, such as
+                    // when there's no existing data.
+                    if (startUp == Config::NETWORK && !config_->standalone())
+                        m_networkOPs->setNeedNetworkLedger();
+                    startGenesisLedger();
+                }
+                else
+                {
+                    return false;
+                }
             }
         }
         else if (startUp == Config::NETWORK)
@@ -2007,7 +2020,7 @@ ApplicationImp::loadOldLedger(
             return false;
         }
 
-        if (!loadLedger->walkLedger(journal("Ledger")))
+        if (!loadLedger->walkLedger(journal("Ledger"), true))
         {
             JLOG(m_journal.fatal()) << "Ledger is missing nodes.";
             assert(false);